redesign the header API

I'm quite satisfied with this right now (though this doesn't say
anything about how I feel about it tomorrow), but it's ugly that some
guts (headers.Base) are exposed in the public API.

1 files changed, 60 insertions, 0 deletions

diff --git a/headers/string.go b/headers/string.go
new file mode 100644
index 0000000..9979aef
--- /dev/null
+++ b/headers/string.go
@@ -0,0 +1,60 @@
+/******************************************************************************
+*
+*  Copyright 2018 Stefan Majewsky <majewsky@gmx.net>
+*
+*  Licensed under the Apache License, Version 2.0 (the "License");
+*  you may not use this file except in compliance with the License.
+*  You may obtain a copy of the License at
+*
+*      http://www.apache.org/licenses/LICENSE-2.0
+*
+*  Unless required by applicable law or agreed to in writing, software
+*  distributed under the License is distributed on an "AS IS" BASIS,
+*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+*  See the License for the specific language governing permissions and
+*  limitations under the License.
+*
+******************************************************************************/
+
+package headers
+
+//String is a helper type that provides type-safe access to a Swift header key
+//whose value is a string. It cannot be directly constructed, but some subtypes
+//of schwift.Headers have fields of this type. For example:
+//
+//    var hdr AccountHeaders
+//    //the following two statements are equivalent:
+//    hdr.Set("X-Container-Read", ".r:*,.rlistings")
+//    hdr.ReadACL.Set(".r:*,.rlistings")
+//    //because hdr.ReadACL is a headers.String instance
+type String struct {
+	Base
+}
+
+//Exists checks whether there is a value for this header.
+func (f String) Exists() bool {
+	return f.H.Get(f.K) != ""
+}
+
+//Get returns the value for this header, or the empty string if there is no value.
+func (f String) Get() string {
+	return f.H.Get(f.K)
+}
+
+//Set writes a new value for this header into the corresponding schwift.Headers
+//instance.
+func (f String) Set(value string) {
+	f.H.Set(f.K, value)
+}
+
+//Del removes this key from the original schwift.Headers instance, so that the
+//key will remain unchanged on the server during Update().
+func (f String) Del() {
+	f.H.Del(f.K)
+}
+
+//Clear sets this key to an empty string in the original schwift.Headers
+//instance, so that the key will be removed on the server during Update().
+func (f String) Clear() {
+	f.H.Clear(f.K)
+}